It is well known that laser devices, like all semiconductor devices, are subject to current and voltage spikes (surges) which occur often in use. Such spikes can be caused by electrostatic forces, power supply malfunctions, etc. In semiconductor lasers, such spikes cause degradation of performance and are known to occur in the reverse bias mode.
Copending application, Ser. No. 08/386,413, filed Feb. 10, 1995 and assigned to the assignee of the present application (now U.S. Pat. No. 5,550,852, issued Aug. 27, 1996) discloses the use of a second laser of opposite conductivity type from that of a first laser and fabricated along with the first laser diode for surge protection. The second diode is arranged electrically in parallel with the first diode and is operative in the reverse diode mode. The use of the second diode in this mode avoids damage even during manufacture and has been found to increase yields significantly.